title: Monitoring of extra-axial brain tumor response to radiotherapy using pseudo-continuous arterial spin labeling images: preliminary results.
abstract: BACKGROUND
  Technological developments have increased the ease of performing perfusion MRI by arterial spin labeling (ASL) in clinical settings. The objective of this study was to evaluate the effects of radiotherapy on extra-axial brain tumors by using MR perfusion images obtained using the pseudo-continuous arterial spin labeling (pcASL) method.
  
  
  METHODS
  Six consecutive patients (nine lesions) with extra-axial brain tumors treated only with radiotherapy were enrolled in this study. MR examinations, including pcASL imaging, were performed before and after radiotherapy. Cerebral blood flow, maximum tumor blood flow (mTBF), tumor volume and the ratio of signal enhancement by contrast material (enhancement ratio) were evaluated in serial examinations during the course of radiotherapy. Both the percentage change in mTBF (mTBF ratio) and the percentage change in volume (volume ratio) were calculated using values obtained before and after radiotherapy. The correlation between the volume ratio and the mTBF ratio was assessed using linear regression analysis and Spearman's rank correlation coefficient (rs).
  
  
  RESULTS
  A strong correlation was demonstrated between the tumor volume ratio and the mTBF ratio before and after radiotherapy (rs=0.93, P<.01). However, no significant correlation was identified between changes in enhancement and volume ratio (rs=0.20) or between changes in enhancement and mTBF ratio (rs=0.30) before and after radiotherapy.
  
  
  CONCLUSIONS
  The mTBF measured using pcASL may serve as an additive index for tumor volume when determining tumor response to radiotherapy even in the absence of contrast material.
authors.affiliation: Department of Radiology, Faculty of Medical Sciences, University of Fukui, Fukui, Japan. Electronic address: yamatatu_01eik@yahoo.co.jp.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kinoshita
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kosaka
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Sato
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shioura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Takeuchi
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Kimura
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000473:pathology / Q000532:radiotherapy; D002536:Cerebral Arteries / Q000473:pathology*; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008577:Meningeal Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D008579:Meningioma / Q000473:pathology* / Q000532:radiotherapy*; D008875:Middle Aged; D010865:Pilot Projects; D061089:Radiotherapy, Image-Guided / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013113:Spin Labels; D016896:Treatment Outcome
chemical_list: D013113:Spin Labels
keywords: Extra-axial brain tumor; Monitoring; Pseudo-continuous arterial spin labeling; Radiotherapy